Process of refining hydrocarbon oils



Aug. 14, 1934. RB. DAY 1,970,284

PROCESS OF REFINING HYDROCARBON OILS I Filed May 25, 1932 a Sheets-Sheet 1 CONDA'A SZQ pram :2

Aug. 14, 1934. R. B. DAY

I PROCESS OF REFINING HYDROCARBON OILS Filed May 25, 1932 3 Sheets-Sheet 2 GOP Q8 cow com

Aug. 14, 1934. i R. B. DAY

PROCESS OF REFINING HYDROCARBON OILS 3 Sheets-Sheet 5 Filed May 25, 1932 HYDDOLHLODIC ACID REQUIRED F0l2 TQEATMENT GAUGE PRESSUIZELBS PERSQUARE INCH FIGS.

Patented Aug. 14, 1934 .1 PROCESS OF REFIgTIlgG HYDROCARBON Roland B. Day, Chicago, Ill., assignor to Universal Oil Products Company; Chicago, Ill., a'corporation of Delaware Application May 25,1932, Serial No. 613,519

7 Claims.

This invention relates to the treatment of hydrocarbon oils and refers more particularly to the treatment of hydrocarbon oil distillates of motor fuel boiling range produced by the'cracking of heavier and less valuable portions of petroleum oils 'though similar motor fuel fractions produced from other sources may also be treated such as those produced in the straight run distillation of crude petroleums or in the cracking of tars producedin the primary distillation of coals, shales, etc.

In a more specific sense the invention is concerned with a process which may be employed to controllably eliminate the undesirable constituents of primary or untreated motor fuel distillates, such constituents being classified generally as the gum-forming and colored compounds and the sulphur-containingderivatives, the latter imparting a bad odor to the distillates, and being corrosive upon the metal parts of automobile engines either before or after combustion.

The most generally used refining method for producing a refined and stable gasoline from primary naphthas consists in regulated treatment of the same with concentrated sulphuric acid, folowed by neutraliaztion (with sweetening if necessary) and redistillation to produce refined gasoline as an overhead product. The disadvantages of this method lie generally in the cost of reagents and particularly in the high losses suifered in accomplishing the desired de gree of refining. The present invention is a departure from the older method and possesses new and useful features which further diiferen-- tiate it from previous attempts to overcome the difficulties encountered in producing a stable refined gasoline from the raw naphtha s produced in cracking operations with minimum losses.

, Other features and advantages will become evidentin the development of the specification.

In one specific embodiment the invention comprises the treatment of hydrocarbon oil distillates, particularly cracked hydrocarbon oil distillates of approximate motor fuel boiling range at elevated temperatures and under pressures sufiicient to substantially prevent vaporization of said distillates with hydrochloric acid and minerals and/or ores of -metals.

The ores of a considerable number of metals have been found to be suitable for use in the process such as the ores of zinc,-tin, iron, copper, lead, and others. The treating efiect produced by any particular mineral or ore, or mixture of minerals and ores which may be employed in conjunction with hydrochloric acid in the process will be PATENTv OFFICE distinctive in any case so that while a number of alternatives are possible, they are not exact equivalents. 1

The following list of zinc minerals indicates the type of naturally occurring metal compounds '60 which may be employed as such or mixed with gangue materials in naturally occurring ores and in general it may be stated that analogous compounds of other metals, particularly heavy metals whosehalides have polymerizing action may also be employed, each with its particular efiect in any given case. In some instances the gangue materials present may act as spacing agents to distribute the active mineral and thus provide greater contact surface; However, in some cases additional inert spacing materials may be supplied if the minerals occur in relatively concentrated form or if concentrates produced by flotation, electrical separation, etc. are available. Among the silicates of zinc, Willemite or Troostite may be employed, these minerals being zinc orthosilicates of the general formula Zn2SiO4 or 2ZnO.SiOz. In these silicates manganese and iron may be isomorphous with the zinc, the percentage of manganese oxide present being as high as 12% in some cases and the percentage of ferrous oxide as high as 2%. These ores occur in the Franklin furnace region of New Jersey. Another zinc silicate mineral is Calamine which has a. formula of H2Zn2SiO5 or H2O.2Zn0.SiO2 using the oxide formula. .This mineral is available in various localities in the United States, such as New Jersey, Pennsylvania, Virginia and Missouri. g

The carbonate mineral Smithsonite, ZnCoa 130 may be employed; this mineral also containing iron and manganese carbonates in many instances. It occurs with Galena and Sphalerite, and is found in New Jersey, Pennsylvania, Wisconsin, Minnesota, Missouri and Arkansas in considerable quantities.

The mineral Aurichalcite is a hydrated carbonate of Zinc and. copper in isomorphous mix-' ture, numerous analyses having established the general formula 2(Zn, Cu) CO3.3(Zn, Cu) (OH) 2. me This particular ore occurs in quantity in deposits in Beaver County, Utah, and represents a particular case in. which the ore contains an electropositive and an electronegative metal in isomorphous form.

The mineral Hydrozincite having the formula ZnCO3.2Zn(OH) 2 or 3ZnO.CO2.2H2O is considered to be a variety of Smithsonite with which it frequently occurs and represents a case of a relatively pure zinc mineral which may be used to 110 advantage in treatments upon relatively low vsulphur naphthas or gasolines.

It is comprised within the scope of the invention to employ mixes or blends of naturally occurring ores or minerals with the particular object of controlling the relative proportions of electropositive and electronegative metals present since in many cases the relative amounts of degumming and desulphurizing reactions respectively appear to be a function of the relative amounts of electropositive and electronegative metals present in the ores. It is possible that this effect is due to the initial formation and subsequent decomposition by hydrochloric acid of sulphides formed by the action of organically combined sulphur or free hydrogen sulphide upon the electronegative metals. This phenomenon, however, does not always occur and cannot be laid down as an absolutely general rule.

An important feature of the invention appears in the fact that while treatments are conducted at elevated temperatures that suflicient pressure is held upon the system to maintain the oils insubstantially liquid phase. I have determined that when treating cracked distillates that unexpectedly good treating effects in regard to selective removal of gum-forming compounds and sulphur reduction are produced when utilizing temperatures within the approximate range of 500 and 650 F., the pressure required to maintain cracked distillates containing substantial amounts of gasoline boiling range fractions in liquid phase being of the order of from 400 to 500 pounds per square inch under these temperature conditions. The exact temperature employed in the treatment will depend upon a number of factors, particularly upon the chemical composition and boiling range of the naphtha or gasoline undergoing treatment and the mineral or mixture of minerals or ores which may be selected for use in conjunction with hydrochloric acid.

The beneficial effects of pressure sufiicient to insure substantially liquid phase conditions may be due to several causes. It is probable that the reactions of polymerization and desulphurization proceed with greater velocity in the liquid phase and under increased pressure conditions. At the same time the capacity of treating equipment for permitting a suflicient time factor is lowered so that the construction of a suitable plant is less costly than if any appreciable degree of vaporization is permitted.

When stabilized distillates are employed which are substantially free from dissolved gases and low boiling hydrocarbons whose critical temperatures may be below the temperatures employed in the treatment, considerably lower pressures may be employed than when unstabilized or poorly stabilized distillates are employed. The curves shown in Figure 2 indicate the limit conditions of operation which must be adhered to in treating two gasolines of 114 and 128 mean molecular weight respectively if substantially liquid phase treating conditions are to be maintained.

The nature of the reactions which have been found to produce the unusually good refining effects observed upon cracked gasolines when treated according to the process of the invention is difficult of exact determination on account of the complex character of the hydrocarbon distillates, particularly in regard to the chemical nature of the gum-forming compounds and the form of combination of the sulphur which is present.

It may be assumed that thegum-forming compounds consist to a large extent of diand triolefins of a conjugated character since these compounds are known to readily undergo polymerization. The sulphur compounds may be mercap tans, sulphides, disulphides, thioethers, thiophenes, etc., besides hydrogen sulphide.

The following equations suggest a possible explanation of the course of the reactions of treatment:

, These equations assume that hydrochloric acid is the active material in producing reactions of polymerization among compounds such as the diand tri-olefins which are present in cracked distillates, the minerals or metal chlorides formed from them by the action of the acid thereon functioning catalytically. However, it is possible that the reactions involve some formation of intermediate addition compounds between metals, metal oxides and/or metal chlorides and the hydrocarbon radicals. The determination of the exact course of the reactions of the treatment is beset with great difiiculties both from the experimental and analytical standpoint. A small amount of moisture must be present to insure effective treatment, the necessaryv quantities being formed as a result of the action of hydrochloric acid upon the minerals or ores or being introduced along with the hydrochloric acid. The addition of any excess of water above a certain minimum requirement has been found to be quiteuniformly detrimental to the eflicacy of the treatment, and in some instances particular minerals or ore mixtures may need to be chosen whose rate of reaction with hydrochloric acid is slow enough so that no substantial excess of water is produced. Obviously any mineral or ore obtained from the mine in a wet condition will require a certain degree of dehydration by heat treatment to reduce the water content to the permissible limit. v

To account for the extraordinary efliciency of the process in removing sulphur from cracked distillates which are refractory from the standpoint of ordinary sulphuric acid treatments, two types of reactions may be considered, the first involving polymerization of sulphur compounds along with the highly unsaturated hydrocarbons so that the sulphur appears in the heavy polymers and, second those involving a preliminary combination of organic sulphur with a metal to form metal sulphide which is later decomposed by hydrochloric acid to evolve hydrogen sulphide as a gas. These reactions are merely assumed and their proof would involve a series of difiicult analyses which if not impossible would add little value to the present specification. Some evidence is at hand to shOW that combined sulphur in high sulp'hur oils may appear after the treatment in mercaptans as a result of secondary reactions of. hydrocarbons with hydrogen sulphide originally formed. However, with suitable precautions which will be developed in connection with a description of an operation, this tendency toward required in the treatments.

essary small amounts of acid. On account of the complex nature of many minerals and ores that may be used, the exact efi'ect of hydrochloric acid upon their chemical composition and physical structure is not always predictable. In some cases it may be of advantage to precondition the ores by treatment with hydrochloric acid to form some amounts of chlorides while in other cases the compounds involved may undergo only a minor decomposition so that the consumption of I hydrochloric acid-in such reactions is negligible.

There is apparently some definite relationship between the amount of hydrochloric acid necessary for efficient treatment and the pressure employed upon the system which is shown by the curve in Figure 3. An inspection of this curve indicates that at the preferred pressures, to-wit: 400 to 600 pounds per square inch, that the consumption of hydrochloric acid is reduced to a practical minimum whereas it increases sharply at lower pressures. Aside from the effect of greater concentration of the hydrochloric acid due to the use of higher pressures than have heretofore been employed in similar treating processes, it is possible that the hydrochloric acid functions with metal ores and minerals (and possibly metal chlorides produced therefrom) in a concentrated solution considerably above it maximum solubility in water at ordinary pressures. The treating ef-' fects observed may thus be due to the joint action of hydrochloric acid and metal chlorides in the presence of extremelysmall amounts of moisture. The small amount of hydrochloric acid necessary for the treatment may be added as a substantially dry gas or in concentrated solution as may be found necessary for producing the best treatment in any particular case.

The process may be conducted in any suitable type of apparatus and Figure 1 shows diagrammatically by the use of conventional figures in side elevation the essential features of a plant layout whichcan be used.

Distillates to be treated may be introduced to the plant through a line 1 containing a control valve 2 and pumped by a pump 3 through a line 4 containing control valve 5 into and through a heating element 6 disposed to receive heat from a furnace 7. After being brought to a suitable temperature for treatment the heated products may be discharged through a line 8 containing a control valve 9 and leading to a line 10. Acid necessary for the treatments may be supplied'to a pump 18 through a line 16 containing a control valve 1'7 and discharged through a line 19 containing a control valve 20 into line 10 where it mixes with the heated oils. As previously stated the acid may be introduced in a solution of proper concentration to insure the presence of the small amounts of water which are apparently necessary in the treating reactions or may be introduced as a substantially dry gas, the type of pumping equipment represented by number 18 being suitably modified.

The acid and oil pass under selected temperatures and pressure conditions within the ranges previously mentioned through valve 11 and enter pressure treater 12 which contains a mineral contact mass 13 dividing the interior of the treater into upper and lower liquid; spaces 14 and 15 respectively. During the passage of the oil and acid through the contact mass, degumming and desulphurizing reactions are effected and the products 'of the treatment pass through line 21 containing control valve 22 to fractionator 23,

valve 22 being so manipulated in conjunction with valves subsequent to the fractionator that the pressure obtaining on the pressure treater is substantially reduced in the fractionator which may operate, for example, at pressures of from 50 to 100 pounds per square inch.

Higher boiling fractions than are desired in the finished gasoline appear in the fractionator as heavy polymer refluxes and comprise high boiling and substantially unaifected hydrocarbon fractions which' may have been present in the' raw naphtha if such was treated, and also polymersof olefins. Some sulphur may appear in the polymers in the case of high sulphur stocks and some of the original sulphur may be present in the fractionator in the form of hydrogen sulphide. It is frequently advantageous in the case of high sulphur oils to utilize pressure treaters in series, the hydrogen sulphide formed in the treating reactions in the first of such a series being vented before further contact is brought about, thus reducing the tendency of metal sulphide formation with corresponding depreciationin the value of the contact materials. By venting the fixed gases and thus removing the majority of hydrogen sulphide present, the formation of mercaptans may be reduced to a practical minimum so that the desulphurization is more effective.

Any hydrochloric acid which may be lost when i the hydrogen sulphide and other low boiling hydrocarbons or fixed gases are released may be counter-balanced by further additions of acid prior to the succeeding pressuretreater. The

vented gases may be passed through auxiliary beds of granulated metals and the chlorides and sulphides recovered if desired.

The refluxes from fractionator 23 may be re-- moved through a line 24 containing a control valve 25 and disposed of in any suitable manner. In case these refluxes are of fairly low sulphur content and otherwise suitable, they may be used as recycle stock in the cracking plant which may have produced the naphtha or gasoline treated. The vapors and fixed gases from the fractionator may be conducted through a vapor line 26 containing control valve 27 and be cooled during passage through a condenser 28, the cooled gases and condensed gasoline passing through a rundown line 29 containing control valve 30 to a able upon 'difierent stocks could be multiplied to w a considerable extent. A few, however, will sufiice to show the advantages of the process over the more commonly used systems of treatment.

'An untreated cracked gasoline made from a relatively high sulphur California charging voil 15c may be treated in equipment generally similar to that shown in Figure 1 at a temperature of 565 F. and a pressure of 475 pounds per square inch. The contact mass employed in the pressure treater may consist of a zinc silicate ore, and hydrochloric acid may be admitted to the treating zone at a rate corresponding to from 0.2 to 0.3 pounds per barrel of finished gasoline, the small amount passing out of the treating zone being absorbed during passage of the treated oils and fixed gases through auxiliary beds of metal turnings. The following table shows the relative properties of the raw or untreated gasoline and the properties of the finished gasoline, the properties of the latter being determined after the passage of approximately 6000 barrels of gasoline through 1 ton of contact materials.

Comparison of raw and treated gasolines Raw Treated Color Red. +30 Color stability-.. 26 Mg. of gum/100 cc. 300 20 Total sulphur 0. 38 0.14 Doctor test Positive. Negative. End point F 404 402 Odor Bad Good.

After 4 hours exposure to sunlight.

A further example may be cited involving the treatment of cracked gasoline from a Mid-continent semi-asphaltic residuum. The conditions of operation may be substantially the same as those given in the first example and the proper- After! hours exposure to sunlight. A I

The results obtained by the process as evidenced by the two preceding examples are striking from several standpoints. It was observed that in both cases the color and color stability were better than those obtainable even by the use of commercially prohibitive amounts of sulphuric acid as shown in other experiments. The gum content was reduced to a figure below that required in premium gasolines and the odor was perfectly sweet. In the first example the sulphur reduction isespecially noteworthy since California pressure distillates are notoriously refractory in regard to desulphurization by sulphuric acid or other methods of treatment.

The treating losses sufiered were considerably less than 1% in both cases and this fact coupled with the extremely high quality of the treated product is of itself sufiicient to recommend the in regard to the removal of gum forming olefins without affecting mono-olefins is evident from the second example in the maintenance of the octane number after treatment while the oxygen bomb test which generally indicates the stability of the gasoline on storage is raised to a point considerably in excess of the minimum of 240 minutes which is at present accepted as indicating a gasoline sufficiently stable under average storage conditions.

The foregoing disclosure of the nature of the invention and the numerical data presented in support of its commercial value are sufficient for their respective purposes but none of the particular details given are to be construed as im-' posing limitations on the process which is generally broad in scope.

I claim as my invention:

1. A process for refining gasoline-containing distillate to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the same at elevated temperatures to the action of hydrochloric acid in the presence of a contact agent comprising a zinc ore under sufficient pressure to maintain a substantial portion of .the distillate in liquid phase during the treatment.

2. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the hydrocarbon oil at elevated temperatures to the action of hydrochloric acid while in the presence of a contact agent comprising an ore of a metal, selected from the group consisting of zinc, tin, iron, copper and lead, a substantial portion of the said hydrocarbon oil being maintained in the liquid phase during the treatment thereof.

3. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the same at elevated temperature to the action of hydrochloric acid in the presence of a contact agent comprising a zinc ore under sufficient pressure to substantially prevent vaporization of the distillate during the treatment.

4. A process for refining hydrocarbon oil to remove color and reduce the gum and sulphur content thereof, which comprises subjecting the pbrtion thereof in liquid phase with hydrochloric acid in the presence of a silicate of zinc.

6. A process for refining hydrocarbon oil which comprises treating the same at elevated temperature and while maintaining a substantial portion thereof in liquid phase with hydrochloric acid in the presence of a carbonate of zinc.

'7. A process for refining hydrocarbon oil which comprises treating the same at elevated temperature and while maintaining a substantial portion thereof in liquid phase with hydrochloric acid in the presence of zinc ore containing zinc and copper.

' ROLAND B. DAY. 

